The present invention relates generally to an improved drive means for the lift-auger utilized in pneumatic spreader systems for distribution of granular agricultural crop treating chemicals, and more particularly to a system for achieving uniform distribution of such materials through the use of an improved drive means for initiating the rotation of the lift-auger, and for maintaining the rotation thereof while in the normal running mode. The apparatus of the present invention is designed to provide dual-torque ranges and dual-rotational speeds to accomplish initial rotation of the auger upon start-up, followed by maintaining the rotation at a constant rate while in the normal running mode. The drive system of the present invention is effective for achieving uniform rates of application, particularly at the point of initial start-up following an interval of shut-down of the lift-auger.
Pressurized pneumatic systems utilizing a single distribution head delivering or metering a supply of granular or particulate material for controlled discharge of such material from a plurality of elongated booms have been employed in the past, however the systems currently in use normally deliver granular products through use of a lift-auger which is designed to rotate under conditions of substantially constant speed and constant torque. Occasionally, and particularly when the system has been shut-down for an interval of time with material remaining in the lift-auger, some uneven flow may occur at the time of lift-auger start-up. The non-uniformity may result from the packing of particulate material within the auger during the interval of shutdown, and upon start-up, the rotation of the lift-auger may occur in a non-uniform fashion. The present invention provides a reliable system for maintaining the distribution and application rate at a substantially uniform and constant level through the active booms.
Agricultural techniques require the utilization of soil treating agents to either encourage, discourage, destroy, or inhibit plant growth. Such agents may generally be characterized as crop treating chemicals, and include materials designated as nutrients such as fertilizers, and pesticides such as insecticides and herbicides including pre-emergent and/or post-emergent growth inhibitors. Accordingly, the term "crop treating chemical" is used in a comprehensive sense to incorporate those various ingredients utilized in agriculture to treat either the soil, the growing crop or plants, or certain insects which may damage the crop. Active materials used for treatment are commonly found in one of three forms, either water soluble, water wettable, particulate solid or in surface-impregnated solid form. In connection with the present invention, granular materials and/or surface-impregnated (wetted) granular materials are of particular interest, with the system of the present invention being particularly adapted for use in connection with the selective and uniform distribution of such materials through the system and onto the soil or other surfaces being treated.
In the treatment of agricultural fields and crops through spreading of one or more active treating ingredients, the efficiency of the treatment operation may be enhanced if the distribution of the ingredients is maintained at a uniform and/or controllable rate particularly at point of initiation of lift-auger rotation. Uniform application rates have become an important factor, particularly with the use of certain pesticides and/or herbicides which require a predetermined application rate in order to be effective, and not harmful to the crop being treated. Occurrences of under-application or over-application of crop treating materials may result in application being either ineffective or, in certain instances, harmful to the crop. Additionally, the efficiency of the operation may be enhanced if the actual load required to be carried by the spreading equipment is reduced. Therefore, the utilization of dry particulate solids will substantially reduce the load requirement, inasmuch as water or other treatment medium or treatment vehicle is not required The need for multiple passes may be reduced if surface-impregnated granular material may be uniformly spread, such as through the use of a granular fertilizer having a surface impregnated with a particular pesticide. The utilization of pressurized pneumatic systems will normally eliminate or substantially reduce the vehicle load by eliminating the need for large quantities of water, since pneumatic systems normally utilize a compressor to generate a supply of compressed air in lieu of a liquid plus liquid pressure source as a means to create a medium for accomplishing delivery of the treating ingredient onto the soil.
Pneumatic spreader systems typically are mounted upon self-propelled vehicles, thereby providing a means for achieving the distribution. In order to render these systems efficient, elongated booms are employed, and it is not uncommon for such booms to extend outwardly a distance of 20 feet or more from the center axis of the vehicle. When the operator reaches the end of a field, the entire capability of the system is shut down for turn-around to avoid any excessive or double-coverage. In order to render the system more highly advantageous, this interruption of flow is achieved while maintaining substantially uniform application rates upon start-up. An added advantage of the system permits intermittent shut-down of certain booms when the fertility index varies across the field being treated, with uniform distribution being achieved upon the occurrence of start-up.
During normal operation, the lift-auger becomes loaded with granular material. In those instances when the machine reaches the end of the field, and is being turned around for initiation of the next application run, the material remaining in the auger tends to flow downwardly along the ramp formed by the auger flutes, thereby becoming more densely packed within the confines of the auger. Occasionally, on these occurrences, the auger resists initial start-up until the packed material breaks away, and auger rotation is commenced. Initiation of auger rotation accordingly requires higher-than-normal torque, and preferably lower-than-normal running rates until complete breakaway occurs. In most instances, the interval of time required for break-away is equivalent to somewhere between 180 degrees of auger rotation, or somewhat greater period. In order to accomplish the desired results, the system initially operates in a low-speed high-torque mode until pressure in the system driving the hydraulic motor rotating the auger reaches a certain predetermined level. For most common systems, this low-speed high-torque mode will be retained until the system pressure reaches approximately 100 psi. By way of example, the normal operating pressure of a typical system of this type is 300 psi, it being understood that a pressure of 100 psi is a level which while below, is substantially equal to normal operating pressure. At that point in time, the system is designed to switch to the high-speed low-torque mode for continuous and ongoing operation. A spool valve is commonly utilized to achieve this conversion. In this fashion, the lift- auger reaches its high speed operational mode promptly, thus reducing the tendency toward pulsations in product delivery.
As indicated, uniformity of distribution of particulate materials depends to a certain extent upon operation of the entire system, including the distribution head, the material transferring conduits, as well as the lift-auger In order to preserve operational integrity and predictability, therefore, uniformity of rate of rotation of the lift-auger is a desirable objective and goal. The features of the present invention permit intermittent shut-down of the system, it having been found that operation of the system may be resumed while preserving uniformity of ongoing distribution of particulate solids from the system. The features of the present invention have been found desirable for improving the performance of systems utilizing lift-augers, and particularly for improving the performance of such systems when the operation of the lift-auger has been temporarily interrupted.
This uniformity of performance is achieved through the utilization of a lift-auger drive system which employs dual-torque ranges as well as dual rates of rotation.